Fluctuations In Metal Concentrations Research Articles

Monitoring metals in South African harbours between 2008 and 2009, using resident mussels as indicator organisms

More than 65% of the South African coastline is threatened as a result of pollution, a large proportion of which is land derived. To date the majority of published data on metal monitoring has been on limited regions or once-off sampling events. In this paper, we present the first data on metal exposure at sites along the eastern seaboard of South Africa in resident brown mussels (Perna perna) from six harbour sites (Cape Town, Durban, East London, Mossel Bay, Port Elizabeth and Richards Bay Harbours) over a two-year period (2008 and 2009). These data do not represent historical or the current metal exposure levels, but rather an indication of the degree of metal exposure fluctuations over two years at the same site. Metal accumulation of aluminium, arsenic, cadmium, cobalt, chromium, copper, iron, manganese, molybdenum, nickel, lead, selenium, strontium, uranium and zinc was determined by thermo-inductive coupled plasma mass spectrophotometry. The results showed marked fluctuations in metal concentrations between years and identified Cape Town, Mossel Bay and Port Elizabeth Harbours as those sites where mussels had the highest metal levels. Statistically significant variations in metal concentrations were observed between the two sampling periods and the six harbours. Metal concentrations decreased from 2008 to 2009, which was largely attributed to changes in ambient metal concentrations, as a result of variable non-point discharges of metals into the harbours and larger-scale oceanographic changes in upwelling events. The results further emphasise the necessity for annual monitoring of the South African marine environment.

The load of heavy metals leaching from grassland in central Ner River valley

Łódź is the largest Polish city in the zone of the main watershed of the country. The watershed zone offered a dense network of small streams, mostly belonging to the Ner River catchment. The use of the Ner River as a collector of industrial sewage caused the accumulation of high amounts of heavy metals in the river sediments and arable land, intensively fertilised with the waters of the Ner River for more than 40 years. Due to the continuation of irrigations in the river valley, water with a substantially lower degree of contamination with organic substance and biogens returns to Ner from the grassland complexes. The objective of the study is the determination whether improvement of water quality subject to circulation within the grassland complexes also concerns heavy metals. The study area covers grassland complexes in the middle section of the Ner River valley, between the weir in Charbice Górne and Jeżew. Due to the variability of acidic-alkaline and oxidation-reduction conditions caused by variable moisture of the soil containing high amounts of allochtonic (post-sewage) organic matter, the observed grassland complexes show liability in terms of retention and release of the analysed metals to Ner. In summer 2018 on the analysed grassland complexes, conditions favouring the emission of all studied metals occurred. This evidences what the discontinuation of irrigation of grassland complexes, previously irrigated with sewage from Łódź, can lead to. The comparison of sites located along the course of the Ner River also provides a complex image of changes in concentrations, with evident fluctuations of metal concentrations.

Heavy metal bioaccumulation and risk assessment for wild and farmed beluga sturgeon caviar

Because of over-exploitation of sturgeon for caviar production, they have been listed worldwide in annex II of the Convention on International Trade in Endangered Species regulations; so caviar production using aquaculture is increasingly seen as a feasible way to reduce overfishing. The accumulation of the nonessential metals As, Ba, Cd, Hg, Pb, and Sn was determined in the caviar of farmed and wild Beluga sturgeon (Huso huso). The levels of As in both and Cd in wild samples were less than 0.01 mg kg(-1) wet weight, and the comparison for all of the metals studied did not show large fluctuations in metal concentrations between farmed and wild caviar samples. The average for each toxic metal was below the permissible limits proposed by the UK's Ministry of Agriculture, Fisheries and Foods (2000). The maximum allowable daily consumption rate of caviar was calculated; however, the health risks from caviar consumption are uncertain because the amount of caviar consumed by heavy users is not known.

Metal accumulation and oxidative stress biomarkers in octopus (Octopus vulgaris) from Northwest Atlantic

Metals are ubiquitous in the environment and accumulate in aquatic organisms and are known for their ability to enhance the production of reactive oxygen species (ROS). In aquatic species, oxidative stress mechanisms have been studied by measuring antioxidant enzyme activities and oxidative damages in tissues. The aim of this study was to apply and validate a set of oxidative stress biomarkers and correlate responses with metal contents in tissues of common octopus (Octopus vulgaris). Antioxidant enzyme activity (catalase — CAT, superoxide dismutase — SOD and glutathione S-transferases — GST), oxidative damages (lipid peroxidation — LPO and protein carbonyl content — PCO) and metal content (Cu, Zn, Pb, Cd and As) in the digestive gland and arm of octopus, collected in the NW Portuguese coast in different periods, were assessed after capture and after 14days in captivity. CAT and SOD activities were highly responsive to fluctuations in metal concentrations and able to reduce oxidative damage, LPO and PCO in the digestive gland. CAT activity was also positively correlated with SOD and GST activities, which emphasizes that the three enzymes respond in a coordinated way to metal induced oxidative stress. Our results validate the use of oxidative stress biomarkers to assess metal pollution effects in this ecological and commercial relevant species. Moreover, octopus seems to have the ability to control oxidative damage by triggering an antioxidant enzyme coordinated response in the digestive gland.

Seasonal and annual variations of metal uptake, bioaccumulation, and toxicity in Trifolium repens and Lolium perenne growing in a heavy metal-contaminated field

The reclamation of nonferrous metal-polluted soil by phytoremediation requires an overall and permanent plant cover. To select the most suitable plant species, it is necessary to study metal effects on plants over the time, thereby checking that metals remain stored in root systems and not transferred to aerial parts. In this purpose, the seasonal and annual variations of metal bioaccumulation, transfer, and phytotoxicity in Trifolium repens and Lolium perenne grown in a Cd-, Pb-, and Zn-contaminated soil were also studied. The experimental site was located near a closed smelter. In spring 2004, two areas were sown with T. repens and L. perenne, respectively. Thereafter, the samplings of plant roots and shoots and surrounding soils were realized in autumn 2004 and spring and autumn 2005. The soil agronomic characteristics, the Cd, Pb, and Zn concentrations in the surrounded soils and plant organs, as well as the oxidative alterations (superoxide dismutase [SOD], malondialdehyde [MDA], and 8-hydroxy-2'-deoxyguanosine [8-OHdG]) in plant organs were carried out. Whatever the sampling period, metal concentrations in soils and plants were higher than background values. Contrary to the soils, the fluctuations of metal concentrations were observed in plant organs over the time. Bioaccumulation and transfer factors confirmed that metals were preferentially accumulated in the roots as follows: Cd>Zn>Pb, and their transfer to shoots was limited. Foliar metal deposition was also observed. The results showed that there were seasonal and annual variations of metal accumulation in the two studied plant species. These variations differed according to the organs and followed nearly the same pattern for the two species. Oxidative alterations were observed in plant organs with regard to SOD antioxidant activities, MDA, and 8-OHdG concentrations. These alterations vary according to the temporal variations of metal concentrations. Metal concentrations in surrounded soils and plant organs showed the effective contamination by industrial dust emissions. Metals absorbed by plants were mainly stored in the roots. With regard to this storage, the plants seemed to limit the metal transfer to their aerial parts over the time, thereby indicating their availability for metal phytostabilization. Aerial deposition was another source of plant exposure to nonferrous metals. Despite the occurrence of metal-induced oxidative alterations in plant organs, both plant species seemed to tolerate a high metal concentration in soils. Taken together, these results indicated that T. repens and L. perenne were able to form a plant cover on highly Cd-, Pb-, and Zn-polluted soils, to limit the metal transfer to their aerial parts and were relatively metal-tolerant. All these characteristics made them suitable for phytostabilization on metal-contaminated soils. These findings also highlighted the necessity to take into account seasonal and annual variations for a future phytomanagement. In this work, the behavior of plant species grown in metal-polluted soil has been studied during 2 years. Obviously, this time is too short to ensure that metals remain accumulated in the root system and few are transferred in aerial parts over the time. It is why regular monitoring should be achieved during more than a decade after the settlement of the plant cover. This work will be completed by the study of the T. repens and L. perenne effects on mobility of metals in order to evaluate the quantities of pollutants which could be absorbed by the biota and transferred to groundwater. Bioaccessibility tests could be also realized on polluted soils in order to evaluate the phytostabilization impacts on the exposition risks for humans.

Seasonal change in mental concentrations in selected tissues of the red-knobbed coot, <i>Fulica cristata</i>, from a metal-polluted wetland

The Red-knobbed Coot Frdico cristata is anticipated to be a useful indicator of Cd, Cu, Ni and Pb which are commonly found in effluents and seepage waters from mines, industries and sewage purification works. This investigation was conducted on coots collected from the Natalpruit wetland, which is polluted by metal-containing effluents from mines and sewage works as well as urban runoff. The main objective was to determine whether seasonality can influence the concentrations of these four metals in the liver, kidney, bone and blood of coots sampled during four consecutive winter and summer seasons from 1991 to 1993. Use was made of dried material and analysed with flame atomic absorption spectrophotometry. Cd occurred in the lowest concentrations in all the tissues during all four seasons. Cu in the kidney (22 m/g) and liver (27 m/g) as well as Pb in the bone (33 m/g) and blood (19 m/g) had the highest mean concentrations for the four seasons combined. Only kidney Ni and bone Cd reflected significant (p < 0.05) changes during the four successive seasons. However, in most other cases slight seasonal changes were observed. For instance, the Ph (liver) and Cd (kidney) concentrations were significantly higher during winter 1991 whilst Cd and Cu (both in the blood) were significantly lower during winter 1991 when compared to the succeeding three seasons. Concentrations of Cd and Cu in the liver, Pb in the blood and bone and Cu in the kidney showed no significant seasonal trends. It is concluded that a number of factors in both the abiotic and biotic components may have had an effect on fluctuations in metal concentrations, by acting individually and / or synergistically. Water SA Vol.29(1) 2003: 91-99

Temporal variations of trace metals in aquatic insects

SUMMARY1. Temporal fluctuations were measured in the concentrations of the trace metals cadmium (Cd), copper (Cu) and zinc (Zn) in six insect taxa collected from the same sites in a temperate zone lake over a 14‐month period. The consequences of temporal changes in insect contaminant concentrations for biomonitoring studies are assessed.2. Significant temporal fluctuations in the concentrations of the three metals were measured in almost all of the insect taxa studied. In no case was there a greater than sixfold change in the concentration of a trace metal over the course of the year. The extent of the fluctuations was generally greater for CD, a non‐essential metal, than for the essential micronutrients Cu or Zn.3. Temporal fluctuations in CD concentrations appeared to follow a seasonal periodicity for most taxa. Minima were measured during the winter period in the megalopteran Sialis spp. and in the dipteran taxa Chaoborus punctipennis, Glyptotendipes sp., and Procladius spp., whereas a maximum was measured in the mayfly Hexagenia Hmbata during the same season. In general, temporal fluctuations in Cu and Zn concentrations were less seasonal in character than were those of Cd.4. For some of the taxon—metal combinations studied, temporal fluctuations in metal concentrations could be ignored in biomonitoring studies, whereas in other cases a temporal window of minimum variability should be chosen for the collection of organisms from different sites.

The dispersal of lead, cadmium and nickel from motor vehicles and effects on roadside invertebrate macrofauna

The concentration of lead, cadmium and nickel in air were measured continuously for a 10-month period at sites located at 1·0, 10, 30 and 100 m from a heavily trafficked road in West London. Pollutant dispersion patterns for each metal were established and found to be variable. Concentrations of lead, cadmium and nickel in air were highest in the 0–10 m zone immediately adjacent to the road. Levels of lead, nickel and cadmium in soil were measured on both sides of the road at various distances from the kerbside. It was found that the lead and cadmium levels in soil followed the general pattern established for the same metals in air. Nickel, however, showed only a poor concentration/distance relationship. Metal levels in vegetation were measured three times during the year at sites of increasing distance from the road. Seasonal fluctuations in metal concentrations in vegetation were found but no consistent relationship could be established. Changes in metal content with season appeared to be related to metal type, distance of sampling and position of sampling site, i.e. on the windward or leeward side of the road. A survey of invertebrate macrofauna by means of pitfall traps set out at various distances from the road did not reveal an obvious decline in either numbers of animals caught or in species diversity with increasing metal pollution load in the habitat. Numbers of animals in certain groups (e.g. isopods, hemipterans, collembolans) appeared to increase with proximity to the road.